We propose to study the effects of transplants of fetal retina in the eyes of normal and experimentally blinded rats. Previous studies have shown that intraocular retinal transplants can be successful in promoting interactions between implant and host retinae. To explore this exciting model in depth, six sets of experiments are proposed; these experiments have been designed in order to obtain maximum information on implant-host interactions and on the biology of the implant itself. Briefly, the experiments consist of: fetal retinal implants in intact (I) and aphakic (II) eyes, implants of retinal reaggregates in intact (III) and aphakic eyes (IV), and retinal (V) and reaggregate (VI) implants in eyes whose neural retinae have been damaged by either continuous light exposure or selective neurotoxics. This project will test the following hypotheses: a) that fetal rat retina can be successful transplanted in the adult rat, b) that the transplant will differentiate under these conditions, c) that interrelations may occur between the transplant and the host retina and CNS, d) that implanted cells may repopulate the damaged retina of a blind host.